Muslem Hamood al-Yaqoubi 2020. Developing Social Studies Textbooks for the Ninth and Tenth Grades in the Sultanate of Oman in the Light of Recent Global Trends: (Environmental Education Portal) (Reality - problems - development trends). Journal of Arts, Literature, Humanities and Social Sciences. 54 (Jul. 2020), 345-361. DOI:https://doi.org/10.33193/JALHSS.54.2020.143.